Studies are in progress to investigate some remaining questions about the ribosome cycle. Among these are the role of the free S80 ribosome, the apparent preferential recycling of ribosomes recently released from mRNA, the existence of a translocation step unique to initiation and the relation between release of a completed chain and release of the ribosome from mRNA. These studies are being carried out using a cell free system from reticulocytes which is highly active and a good model for the intact cell.